As known in the art, several different cyclodestruction procedures (i.e., procedures for destroying the ciliary body) have been developed or proposed for treating glaucoma. The clinical standard cyclodestruction procedure employs cryotherapy. Other known cyclodestruction procedures include therapeutic ultrasound and Neodymium:Yag cyclophotocoagulation. However, all of these known cyclodestruction procedures have demonstrated different negative tissue reactions.
Cryotherapy has been characterized by discomfort and edema, therapeutic sound by induced scleral changes, and Neodymium:Yag cyclophotocoagulation has been shown to cause characteristic spotlike conjunctival lesions. Other less specific morbidities have included corneal-scleral thinning, hyphema, cataract, vitritis, retinal detachment, cystoid macula edema, and hypotony. These potential complications have defined cyclodestruction procedures as a last treatment for refractory cases.
In addition to its use in treating glaucoma, cryotherapy is also used to repair retinal detachment by inducing chorioretinal scar formation to close retinal breaks, which chorioretinal scar formation creates adhesions between the retina and sclera. Prior to cryotherapy, radiofrequency diathermy was the standard method used for this purpose. However, radiofrequency diathermy has become less frequently utilized because (1) it requires scleral dissection or was associated with scleral necrosis, and (2) because cryotherapy, which is easier to use with indirect ophthalmoscopy, is associated with less scleral damage and does not require a scleral dissection. However, disadvantages attributed to cryotherapy lesions have been that they have less strength, therefore require more confluence of lesions, and may be associated with greater release of retinal pigment epithelial cells. While ophthalmic lasers have been used to repair retinal detachment, their use has been largely restricted to transpupillary or endoretinopexy applications.